Distributed channel assignment method

• US 6,654,612 B1
• Filed: 06/30/2000
• Issued: 11/25/2003
• Est. Priority Date: 06/30/2000
• Status: Expired due to Term

• Current Assignee: WSOU Investments, LLC (WSOU Holdings, LLC)
• Original Assignee: Lucent Technologies, Inc. (Nokia Corporation)
• Inventors: Ryoo, Jeong-Dong, Mukherjee, Sayandev, Avidor, Dan
• Primary Examiner(s): Maung, Nay
• Assistant Examiner(s): Orgad, Edan
• Application Number:
  US09/607,499
• Time in Patent Office: 1,243 Days
• Field of Search: 455/452, 455/453, 455/450, 455/451, 455/435, 455/436, 455/437, 455/438, 455/447, 455/446, 455/422, 370/329, 370/341, 370/431, 370/455
• US Class Current: 455/450
• CPC Class Codes: H04W 16/14 Spectrum sharing arrangements between different networks
• CPC Class Codes: H04W 24/00 Supervisory, monitoring or testing arrangements
• CPC Class Codes: H04W 4/00 Services specially adapted for wireless communication networks; Facilities therefor
• CPC Class Codes: H04W 72/00 Local resource management
• CPC Class Codes: H04W 72/02 Selection of wireless resources by user or terminal
• CPC Class Codes: H04W 72/541 using the level of interference
• CPC Class Codes: H04W 72/56 based on priority criteria
• CPC Class Codes: H04W 72/563 of the wireless resources

Abstract

Without intercell coordination on a per communication request basis, channel assignment can be efficiently performed by developing for each cell, or a sector thereof when the cells are sectorized using directional antennas, a priority list of groups of channels, and selecting a channel to be assigned in response to a request for service from the highest priority group which has available channels at the time of the service request. The priority lists are developed based on various interference measurements that are made. The priority lists tend to remain the same for relatively long periods of time. However, periodically, the priority lists should be redetermined to insure that the best lists are being employed. For example the lists may need to be changed due to new construction or to seasonal vegetation changes which may affect the interference experienced in the system. Advantageously, system capacity under peak concentrated load conditions may increase. This advantage is further magnified under field conditions for which the cell shapes are not ideal.

Claims

1. A method for assigning a channel in response to a request for service for a wireless terminal of a wireless communication system, the territory served by said wireless communication system being divided into a plurality of regions, said wireless terminal being located in one of said regions, the method comprising the steps of:

developing a prioritized list of channel groups for at least said region in which said wireless terminal is located; and

selecting a channel from the one of said channel groups that has the highest priority of those channel groups that have an available channel within said region,

the method being CHARACTERIZED in that

said prioritized list is developed based on interference measurements which are only made from time to time on a long-term basis.

2. The invention as defined in claim 1 wherein said region is a cell of said wireless communication system.

3. The invention as defined in claim 1 wherein said region is a sector of a cell of said wireless communication system.

4. The invention as defined in claim 1 wherein, in said selecting step, said channel is selected randomly from the available channels of said group of channels having the highest priority and having an available channel.

5. The invention as defined in claim 1 wherein said developing step further comprises the steps of:

determining interregion interference estimates for said fixed wireless communication system.

6. The invention as defined in claim 5 wherein said interregion interference is determined using a common receiver power level at a base station of said region.

7. The invention as defined in claim 1 wherein said method is performed for a plurality of base station is and wherein, each of said base stations performs said selecting step randomly and independently.

8. The invention as defined in claim 1 wherein for each of said regions there is a priority list for uplink channels and a priority list for downlink channels.

9. The invention as defined in claim 1 wherein said developing and selecting steps are performed for uplink channels, the method further comprising the steps of:

developing a prioritized list of downlink channel groups for at least said region in which said wireless terminal is located; and

selecting a downlink channel from the one of said downlink channel groups having the highest priority and having an available channel.

10. The invention as defined in claim 1 wherein each of said regions belongs to a channel reuse cluster, with each region being assigned a primary group of channels, with regions in like positions within a channel reuse cluster being assigned like channels as their primary group of channels, and wherein a highest priority is assigned in said developing step to channels within said primary group of channels for said region.

11. The invention as defined in claim 1 wherein said region is a sector that belongs to a cell, and wherein a channel is considered available only when it is not in use within said cell.

12. A method for processing request for wireless service with a base station serving at least one region, said request being for a wireless uplink channel and a wireless downlink channel, the method comprising the steps of:

developing a first prioritized list of channel groups for at least said region in which said wireless terminal is located, said groups of said first prioritized list being groups of uplink channels; and

developing a second prioritized list of channel groups for at least said region in which said wireless terminal is located, said groups of said second prioritized list being groups of downlink channels;

selecting a channel from the one of said uplink channel groups that is the one of said uplink channel groups of said first prioritized list that has the highest priority from among those uplink channel groups on said second prioritized list that have remaining an available uplink channel in said region; and

selecting a channel from the one of said downlink channel groups that is the one of said downlink channel groups of said second prioritized list that has the highest priority from among those downlink channel groups on said second prioritized list that have remaining an available downlink channel in said region;

the method being CHARACTERIZED in that

each of said first and second prioritized lists is developed based on interference measurements which are only made from time to time on a long-term basis.

13. The invention as defined in claim 12 wherein said region is a sector, and wherein in said steps of selecting a channel from an uplink channel group said channel is selected also only when it is not in use in a cell which includes said sector and wherein in said steps of selecting a channel from a downlink channel group said channel is selected also only when it is not in use in a cell which includes said sector.

14. A method for use in assigning channels to a request for service in a region of a fixed wireless system, the method comprising the steps of:

assigning to each region being served by said fixed wireless system a group of channels as a respective primary channel group in accordance with a fixed channel reuse plan, with each region being a member of a reuse cluster and where like positioned regions within each reuse cluster are assigned the same primary channel group; and

borrowing a channel from a primary channel group of a different region when said region does not have an available channel in its primary channel group to serve said request, said channel being borrowed being a member of a channel group that remains with a highest priority on a prioritized list of channel groups for said region that have not had all of their channels assigned in an area, said prioritized list of channel groups for said region that have not had all of their channels assigned in said area being developed by eliminating those channel groups that have had all their channels assigned in said area from a master prioritized list of channel groups available for use by said region.

15. The invention as defined in 14 wherein said master prioritized list of channel groups available for use by said region includes all groups of channels for uplink use in a cluster including said region.

16. The invention as defined in 14 wherein said area and said region are coextensive.

17. The invention as defined in 14 wherein said area and said region are coextensive and are a cell with said reuse cluster.

18. The invention as defined in 14 wherein said area is a cell and said region is a sector within said cell.

19. The invention as defined in 14 wherein said master prioritized list of channel groups available for use by said region includes all groups of channels for downlink use in a cluster including said region.

20. The invention as defined in claim 19 wherein said master priority list is developed as a function of interregion interference.

21. The invention as defined in claim 19 wherein said master priority list is prioritized so that a channel group less likely to cause interference is given a higher priority than a channel group more likely to cause interference.

22. The invention as defined in claim 19 wherein said master priority list is redeveloped from time to time.

23. A method for use in assigning an uplink channel and a downlink channel to a request for service in a cell of a fixed wireless system in which each group of a plurality of groups of channels is assigned as a respective primary uplink channel group for each cell in accordance with a fixed channel reuse plan and each group of a plurality of groups of channels is assigned as a respective primary downlink channel group for each cell in accordance with said fixed channel reuse plan, with like positioned cells within each reuse cluster being assigned the same primary uplink and downlink channel groups, said cell having a prioritized uplink list of uplink channel groups exclusive of said primary group assigned to said cell and a prioritized downlink list of downlink channel groups exclusive of said primary downlink group assigned to said cell the method comprising the steps of:

assigning an uplink channel for use in serving said request from said primary uplink group of said cell when an uplink channel is available in said primary uplink group of said cell;

assigning a borrowed uplink channel from a primary uplink channel group of a different cell when said cell does not have an available channel in its primary uplink channel group to serve said request, said borrowed uplink channel being a member of an uplink channel group that (i) is a member of a set of uplink channel groups that has as yet not had all of its channels assigned in said cell and (ii) has the highest priority, within said set, according to the prioritization of said prioritized list of uplink channel groups;

assigning a downlink channel for use in serving said request from said primary downlink group of said cell when a downlink channel is available in said primary downlink group of said cell; and

assigning a borrowed downlink channel from a primary downlink channel group of a different cell when said cell does not have an available channel in its primary downlink channel group to serve said request, said borrowed downlink channel being a member of a downlink channel group that (i) is a member of a set of downlink channel groups that has as yet not had all of its channels assigned in said cell and (ii) has the highest priority, within said set, according to the prioritization of said prioritized list of downlink channel groups.

24. The invention as defined in claim 23 wherein the prioritization of said prioritized list of uplink channels is based on uplink interference calculations.

25. The invention as defined in claim 23 further wherein the prioritization of said prioritized list of downlink channels is based on downlink interference calculations.

26. A method for use in assigning an uplink channel and a downlink channel to a request for service in a sector of a cell of a fixed wireless system in which each group of a plurality of groups of channels is assigned as a respective primary uplink channel group for each sector in accordance with a fixed channel reuse plan and each group of a plurality of groups of channels is assigned as a respective primary downlink channel group for each sector in accordance with said fixed channel reuse plan, with like positioned sectors within each reuse cluster being assigned the same primary uplink and downlink channel groups, said sector having a prioritized uplink list of uplink channel groups exclusive of said primary group assigned to said sector and a prioritized downlink list of downlink channel groups exclusive of said primary downlink group assigned to said sector, the method comprising the steps of:

assigning an uplink channel for use in serving said request from said primary uplink group of said sector when an uplink channel is available in said primary uplink group of said sector;

assigning a borrowed uplink channel from a primary uplink channel group of a different sector when said sector does not have an available channel in its primary uplink channel group to serve said request, said borrowed uplink channel being a member of an uplink channel group that (i) is a member of a set of uplink channel groups that has as yet not had all of its channels assigned in said cell and (ii) has the highest priority, within said set, according to the prioritization of said prioritized list of uplink channel groups;

assigning a downlink channel for use in serving said request from said primary downlink group of said sector when a downlink channel is available in said primary downlink group of said sector; and

assigning a borrowed downlink channel from a primary downlink channel group of a different sector when said sector does not have an available channel in its primary downlink channel group to serve said request, said borrowed downlink channel being a member of a downlink channel group that (i) is a member of a set of downlink channel groups that has as yet not had all of its channels assigned in said cell and (ii) has the highest priority, within said set, according to the prioritization of said prioritized list of downlink channel groups.

27. The invention as defined in claim 26 further including the step of developing said prioritized list of said groups of uplink channels and said prioritized list of said groups of downlink channels.

28. The invention as defined in claim 27 wherein said developing step further includes the step of measuring uplink and downlink interference powers.

29. A method for use in assigning an uplink channel to a request for service in a sector of a cell of a fixed wireless system in which each group of a plurality of groups of channels is assigned as a respective primary uplink channel group for each sector in accordance with a fixed channel reuse plan, and wherein each of said sectors is part of its own relative interference cluster, cells of each relative interference cluster being enumerated by index i, with i ranging from 1 to the number of cells in the interference cluster I, with each cell being divided into J sectors, the sectors being enumerated by j, with j ranging from 1 to J, where J is equal to or greater than 1, the method comprising the steps of:

receiving uplink interference measurements from cells that are located within a relative interference cluster of said region;

calculating a quantity indicative of the average uplink interference that is expected to result from use of channel group g by terminals located in sector Sij as $\mathrm{Uij}<br><br>\text{\hspace{1em}<br><br>}<br><br>\left(g\right)=\underset{i^{\mathrm{\prime <br><br>}},j^{\mathrm{\prime <br><br>}}\in <br><br>\mathrm{grp}<br><br>\text{\hspace{1em}<br><br>}<br><br>\left(g\right)}{\sum <br><br>}<br><br>\text{\hspace{1em}<br><br>}<br><br>\underset{i^{\mathrm{\prime <br><br>}},j^{\mathrm{\prime <br><br>}}}{\overset{u}{P}}<br><br>\text{\hspace{1em}<br><br>}<br><br>\left(i,j\right)+\underset{i^{\mathrm{\prime <br><br>}},j^{\mathrm{\prime <br><br>}}\in <br><br>\mathrm{grp}<br><br>\text{\hspace{1em}<br><br>}<br><br>\left(g\right)}{\sum <br><br>}<br><br>\text{\hspace{1em}<br><br>}<br><br>\underset{i,j}{\overset{u}{P}}<br><br>\text{\hspace{1em}<br><br>}<br><br>\left(i^{\mathrm{\prime <br><br>}},j^{\mathrm{\prime <br><br>}}\right)$

 

where

grp(g) is all sectors of the relative interference cluster that were allocated group g as their primary channel group by said reuse plan;

$\underset{i^{\mathrm{\prime <br><br>}},j^{\mathrm{\prime <br><br>}}\in <br><br>\mathrm{grp}<br><br>\text{\hspace{1em}<br><br>}<br><br>\left(g\right)}{\sum <br><br>}<br><br>\text{\hspace{1em}<br><br>}<br><br>\underset{i^{\mathrm{\prime <br><br>}},j^{\mathrm{\prime <br><br>}}}{\overset{u}{P}}<br><br>\text{\hspace{1em}<br><br>}<br><br>\left(i,j\right),$

is the sum of the interference power received by the base station'"'"'s sector receivers in the relative cluster of cell i that were allocated channel group g as their primary channel group by said reuse plan and was caused by transmitters of terminals in sector Sij;

$\underset{i^{\mathrm{\prime <br><br>}},j^{\mathrm{\prime <br><br>}}\in <br><br>\mathrm{grp}<br><br>\text{\hspace{1em}<br><br>}<br><br>\left(g\right)}{\sum <br><br>}<br><br>\text{\hspace{1em}<br><br>}<br><br>\underset{i^{\mathrm{\prime <br><br>}},j^{\mathrm{\prime <br><br>}}}{\overset{u}{P}}<br><br>\text{\hspace{1em}<br><br>}<br><br>\left(i^{\mathrm{\prime <br><br>}},j^{\mathrm{\prime <br><br>}}\right),$

is the sum of the power received by the base station'"'"'s receiver for sector Sij that was generated by the transmitters of all terminals located in sectors of the relative cluster of cell i and allocated channel group g as their primary channel group; and

assigning a priority to each channel group by preemptively assigning the highest priority to the channel group assigned to said sector and thereafter assigning priorities so that channel groups with increasingly smaller value of Uij(g) receive increasingly higher priorities.

30. The invention as defined in claim 29 further comprising the step of selecting a channel to serve said request from the one of said channel groups on said priority list that has the highest priority of those channel groups that has an uplink channel that is not in use within said cell.

31. The invention as defined in claim 30 wherein said uplink channel is selected randomly from those channels in said channel group from which said channel is selected.

32. The invention as defined in claim 29 further comprising the step of taking the necessary interference measurements to calculate $\mathrm{Uij}$

 

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33. A method for use in assigning a downlink channel to a request for service in a sector of a cell of a fixed wireless system in which each group of a plurality of groups of channels is assigned as a respective primary downlink channel group for each sector in accordance with a fixed channel reuse plan, and wherein each of said sectors is part of its own relative interference cluster, cells of said relative interference cluster being enumerated by index i, with i ranging from 1 to the number of cells in the interference cluster I, with each cell being divided into J sectors, the sectors being enumerated by j, with j ranging from 1 to J, where J is equal to or greater than 1, the method comprising the steps of:

receiving downlink interference measurements from cells that are located within a relative interference cluster of said region;

calculating a quantity indicative of the average downlink interference that is expected to result from use of channel group g by base station transmitters located in sector Sij, as $\mathrm{Dij}<br><br>\text{\hspace{1em}<br><br>}<br><br>\left(g\right)=\underset{i^{\mathrm{\prime <br><br>}},j^{\mathrm{\prime <br><br>}}\in <br><br>\mathrm{grp}<br><br>\text{\hspace{1em}<br><br>}<br><br>\left(g\right)}{\sum <br><br>}<br><br>\text{\hspace{1em}<br><br>}<br><br>\underset{i^{\mathrm{\prime <br><br>}},j^{\mathrm{\prime <br><br>}}}{\overset{d}{P}}<br><br>\text{\hspace{1em}<br><br>}<br><br>\left(i,j\right)+\underset{i^{\mathrm{\prime <br><br>}},j^{\mathrm{\prime <br><br>}}\in <br><br>\mathrm{grp}<br><br>\text{\hspace{1em}<br><br>}<br><br>\left(g\right)}{\sum <br><br>}<br><br>\underset{i,j}{\overset{d}{P}}<br><br>\text{\hspace{1em}<br><br>}<br><br>\left(i^{\mathrm{\prime <br><br>}},j^{\mathrm{\prime <br><br>}}\right)$

 

where

grp(g) is all sectors of the relative interference cluster that were allocated group g as their primary channel group by said reuse plan;

$\underset{i^{\mathrm{\prime <br><br>}},j^{\mathrm{\prime <br><br>}}\in <br><br>\mathrm{grp}<br><br>\text{\hspace{1em}<br><br>}<br><br>\left(g\right)}{\sum <br><br>}<br><br>\text{\hspace{1em}<br><br>}<br><br>\underset{i^{\mathrm{\prime <br><br>}},j^{\mathrm{\prime <br><br>}}}{\overset{d}{P}}<br><br>\text{\hspace{1em}<br><br>}<br><br>\left(i,j\right),$

is the sum of the interference power received by all terminal receivers in the relative interference cluster of cell i located in sectors that were allocated channel group g as their primary channel group by said reuse plan and was caused by the base station transmitter of sector Sij;

$\underset{i^{\mathrm{\prime <br><br>}},j^{\mathrm{\prime <br><br>}}\in <br><br>\mathrm{grp}<br><br>\text{\hspace{1em}<br><br>}<br><br>\left(g\right)}{\overset{\text{\hspace{1em}<br><br>}}{\sum <br><br>}}<br><br>\text{\hspace{1em}<br><br>}<br><br>\underset{i,j}{\overset{d}{P}}<br><br>\text{\hspace{1em}<br><br>}<br><br>\left(i^{\mathrm{\prime <br><br>}},j^{\mathrm{\prime <br><br>}}\right),$

is the sum of the power received by all of the

terminal receivers located in sector Sij and that was generated by the base station transmitter of sector within the relative interference cluster of cell i that were allocated channel group g as their primary channel group; and

assigning a priority to each channel group by preemptively assigning the highest priority to the channel group assigned to said cell and thereafter assigning priorities so that channel groups with increasingly smaller value of Dij(g) receive increasingly higher priorities.

34. The invention as defined in claim 33 further comprising the step of taking the necessary interference measurements to calculate $\mathrm{Dij}$

 

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(g)=∑

i′

,j′

∈

grp

 

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(g) 

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

Pi,jd

 

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(i,j)+∑

i′

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∈

grp

 



(g) 

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Pi,ld

 

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35. The invention as defined in claim 33 further comprising the step of selecting a channel to serve said request from the one of said channel groups on said priority list that has the highest priority of those channel groups that has a downlink channel that is not in use within said cell.

36. The invention as defined in claim 35 wherein said downlink channel is selected randomly from those channels in said channel group from which said channel is selected.

37. A method for assigning a channel in response to a request for service for a wireless terminal of a wireless communication system, the territory served by said wireless communication system being divided into at least a plurality of cells, said wireless terminal being located in one of said cells, each of said cells being assigned a primary channel group, the method comprising the step of:

assigning a channel from a channel group that is not the primary channel group for said cell in which said wireless terminal is located, said assigning being performed as a function of a prioritized list of channel groups without coordinating assignment of said channel with any other cell on a per-request basis;

the method being CHARACTERIZED in that

said prioritized list is developed based on interference measurements which are only made from time to time on a long-term basis.

38. The invention as defined in claim 37 wherein said assigned channel is selected randomly from those channels of said channel group from which said channel is assigned in said assigning step.

39. The invention as defined in claim 37 wherein said channel assigned is of a type of one of the types of a set consisting of uplink and downlink.

40. The invention as defined in claim 37 wherein said prioritized list is developed based on interference measurements.

41. The invention as defined in claim 37 wherein said channel assigned is an uplink channel and said prioritized list is developed based on average uplink interference determinations which are derived from interference measurements.

42. The invention as defined in claim 37 wherein said channel assigned is a downlink channel and said prioritized list is developed based on average downlink interference determinations which are derived from interference measurements.

43. The invention as defined in claim 37 further including the step of updating said prioritized list from time to time.

44. The invention as defined in claim 37 wherein said prioritized list is only for a sector of said cell in which said wireless terminal is located.

45. The invention as defined in claim 37 wherein said prioritized list is for said cell in which said wireless terminal is located.